A handful of polio survivors who have spent decades inside so-called iron lungs, have spoken of their existence trapped in ageing machines that have been all but disappeared.

“There are only two or three of us left,” said 70-year-old Paul Alexander. Speaking from Texas, he added: “I’ve tried all the ventilators available and this one is the best. It feels like a more natural way of breathing.”

While cases of the crippling disease still occur in countries such as Laos, Syria and the Democratic Republic of the Congo, it remains endemic in just three - Afghanistan, Pakistan and Nigeria. In the US, it was wiped out in 1979, thanks to the anti-polio vaccine.

In the 1950s, polio outbreaks caused more than 15,000 cases of paralysis each year, according to the Centres for Disease Control. Iron lung machines - pressurised cylinders that draw oxygen into a person’s lungs by creating a vacuum - were once commonplace.

Most people would only need to use the machines for a week or two until they could breathe on their own. For some some polio sufferers with permanent damage to their lungs, they became an essential part of their existence.

As fewer and fewer people used them, the companies who produced them urged people to use alternatives breathing aids. In 2004, one of those corporations, Philips Respironics, told iron lung users they could no longer guarantee they would repair the machines.

Mr Alexander said he was keen to visit Britain (Nick Isenberg/YouTube)

In 2013, the Post-Polio Health International, an organisation which works to help polio sufferers, estimated there were six to eight iron lung users in the United States.

Asked how many there were today, the group’s president, Brian Tiburzi, said: “I don’t have an answer to that. I don’t think anyone knows for certain.”

Gizmodo spoke to three people who still use the machines - Mr Alexander, 70, of Dallas, Martha Lillard, 69, from Oklahoma, and 81-year-old Mona Randolph of Kansas City, Missouri. They may be the very last individuals to rely on this outdated machinery

Mr Alexander, who contracted polio in 1952 when he was six, said he spent nearly every moment in his iron lung, located in the centre of his living room. He answers the phone and types using a plastic wand attached to his mouth.

Remarkably, despite his dependence on the machine, he went to law school and worked as a lawyer.

“When I transferred to University of Texas, they were horrified to think that I was going to bring my iron lung down, but I did, and I put it in the dorm, and I lived in the dorm with my iron lung,” he told the website.

“I had a thousand friends before it was over with, who all wanted to find out what’s that guy downstairs with a head sticking out of a machine doing here.”

Mr Alexander has frequently had problems with maintaining his machine and in 2015 a friend put a video of him on YouTube that explained his problems and of his search for someone who knew their way around an iron lung machine.

“I looked for years to find someone who knew how to work on iron lungs,” said Mr Alexander. “Brady Richards, it’s a miracle that I found him.”

Mr Richards said he visited Mr Alexander once every six months. “The machine is actually the most simple thing on the planet,” he told The Independent. “The problem is that they no longer make the parts.”

Ms Lillard said she was infected with polio when she was five. Now, she spends half of every day in the machine.

“All the mothers were just terrified because people were just getting it right and left,” she told Gizmodo of her infection. “They didn’t know if it was a virus or bacteria or how you caught it.”

Ms Randolph became infected when she was 20. She said she tells children who ask what happened to her that she was damaged by a virus because a vaccine was not available.

She said she was deeply upset when she met anti-vaccine activists.

“Of course, I’m concerned about any place where there’s no vaccine,” she said. “I would just do anything to prevent somebody from having to go through what I have. I mean, my mother, if she had the vaccine available, I would have had it in a heartbeat.”